Keywords
Mediators of inflammation
Major depressive disorder
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Abstract
Objective: To analyze the association between levels of systemic inflammatory markers and symptom severity in adult patients diagnosed with Major Depressive Disorder. Methods: This is an integrative literature review conducted using the PubMed, Virtual Health Library (VHL), and CAPES Periodicals databases, using the descriptors: “Depressive Disorder, Major”, “Inflammation Mediators”, and “Depression”, and truncating the search to: (Depressive Disorder, Major) AND (Inflammation Mediators) AND (Depression). 1,731 articles were found, filtered according to inclusion criteria (Portuguese, English, and Spanish languages; period from 2021 to 2026; full articles) and exclusion criteria (duplicate articles, abstracts, out of scope). Results: Major depressive disorder is associated with a state of low-grade systemic inflammation, with elevated pro-inflammatory cytokines and immunological imbalances. These processes directly influence neurobiological pathways, such as tryptophan metabolism and serotonergic neurotransmission, contributing to the severity of symptoms. Furthermore, inflammation is related to structural and functional brain alterations and an increased cardiometabolic risk, reinforcing its central role in the pathophysiology of major depressive disorder (MDD). Conclusion: Systemic inflammation plays a central role in the pathophysiology and severity of major depressive disorder. Understanding it broadens the possibilities for risk stratification and more targeted therapeutic approaches.
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